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C++ Program To Check Number Is Prime Or Not Using If/Else Statements

A prime number is a number that is greater than 1 and divided by 1 or itself. In other words, prime numbers can't be divided by other numbers than itself or 1. For example 2, 3, 5, 7, 11, 13, 17, 19, 23.... are the prime numbers.

Let's see the prime number program in C++. In this C++ program, we will take input from the user and check whether the number is prime or not.

Check Number Is Prime Or Not Using If/Else Statements In C++

#include <iostream>  
using namespace std;  
int main()  
{  
  int n, i, m=0, flag=0;  
  cout << "Enter the Number to check Prime: ";  
  cin >> n;  
  m=n/2;  
  for(i = 2; i <= m; i++)  
  {  
      if(n % i == 0)  
      {  
          cout<<"Number is not Prime."<<endl;  
          flag=1;  
          break;  
      }  
  }  
  if (flag==0)  
      cout << "Number is Prime."<<endl;  
  return 0;  
}  


Enter the Number to check Prime: 17
Number is Prime.
Enter the Number to check Prime: 57
Number is not Prime.

Conclusion

Here, in this tutorial we have learned how can we check whether the entered number is a prime number or not by using the if-else statements.